Molding apparatus



Feb. 2 1926.

. F. A. K. MARX MOLDING APPARATUS Filed May 25, 1925 /QTT OPA/E VS provide am'ol'ding "souiid and structurally safe,

Patented Feb. 2, 1926.

UNITED STATES FREDERCK A. K. MARX, OF STJLOUIS, MISSOURI.

MOLDING APPARATUS.

Application led May 25, 1925. Serial No. 32,655.

To all whom t may concern:

Be it known that I, FREDERICK A. K. MARX, a citizen of the United States, residing at St. Louis, Missouri, have inventeda certain new and useful Improvementin l\loldin, i Apparatus, of which the following is a full, clear, and exact description, suoli 'as will enable others skilled in the art tok which it appeitains to make and use the saine.

This invention relates to the manufacture of articles and structures of the kind that are formed from a substance which is put in a mold in a plastic state and then allowed to set or harden.

In instances where the article or structure being formed is to have a hollow space or spaces, it is the usual custom to arrange a core in theinold for each of said spaces, then introduce the plastic substances into 'the mold, andthereafter remove said core after said substance has set. `Due to the fact that the plastic substance contacts with the core 'and in many kcases adheres to same, considearble skill and care have tobe exer cised inorder to preventthe molded article from being fractured by the strain to which it is subjected during the operation of reinovingfthe core, and `even when `great care is 'exercised in this operation, tine, hair line cracks areliable to forin in the molded article, which inake it structurally unsafe.

a solid, tapered core is used', it is impracticable to make the molded article more than two or three lfeet in length, because of'this tendency tofractur'e the artitcle or produce hair line ci'acksin saine during the operation of withdrawing the core and because the rdiameter of the widest portion of a relatively long, tapered core would take up so much `of the internal space `of the mold :that the walls of the molded article adja* 'cent the widest poi-tion. of the core would notbe of the proper thickness.

The main object of niy invention is to apparatus of simple design in which cored articles of symmetrical shape and uniform thickness can be formed Equickly and at a lovs7 cost.

Another object of my invention is to provide a molding apparatus that will pro-` duce 'a cored article *or structure which is the apparatus being so 'designed that it eliminates the of the molded article being subfrom being subjected to frictional pressure tendingl to produce hair line cracks in said article, as so often occurs in producing cored articles with molding apparatus of the kind now in use.

To this end I have devised a molding apparatus that comprises a mold of any preferred shape and construction and one or more non-rigid cores adapted to be arranged inside of said mold and leach coinposed primarily of a shell constructed of an inexpensive material having some -fleXi-` bility that is adapted to be left in the molded article after it is completed. Preferably, a collapsible means is arranged inside of the shell so as to support the s ame, prevent it from collapsing or changing mate rially from its original condition, give it the saine rigidity as a solid core, and because of the flexibility of the shell, hold it absolutely straight or to such alignment as may be desired, when the plastic substance is introduced into the mold. The means just referred to is adapted to bev removedfrom the shell, after the substance from which the article is formed has set or hardenedy slightly, but in view of the fact that the shell prevents the plastic substance from contacting with and adhering to said` means, there is no liability of subjecting the molded article yto injurious strains in removing said means. ferred shape in cross section and it can be formed from various materials. One material that l have found to bevery satisfactory is corrugated cardboard, on account of its lowcost; on account of its ability to retain substantially its original shape and form when used in conjunction with "an internal supporting means; on account of the fact that it can be sawed easily; wand on account of the fact that it has suflicient flexi-` bility to permit the internal supporting means of the shell to be easily withdrawn from same without subjecting the molded article to any injurious results when said article is formed from a substance such as gypsum,

Vwhich tends to expand and grip the core tightbeaver board, papier-mch and materialv formed from wood pulp products. Various means can be used for internally supporting the core shell without departing `from the sporit of my invention, so long as vsaid The core shell can be `of any preeye, and rthereby construction of means is of such design that it will afford .sufficient support for the core shell to insure the same retaining substantially its original form, or desired alignment, and is capable of being' easily withdrawn from the shell Without exerting any strain on the plastic material which would tend to produce fractures, even though not perceptible to the render the finished product structurally unsafe. ,My improved molding' apparatus is adaptfor various uses, such', for example, as manufacturing structural shapes, :building Walls, bridges and articles constructed of various kinds of self-hardening, plastic substances. Hoiveveiyit is particularly adapted for use in the manufacture of gypsum articles, on account of the fact that it permits Vsaid articles to be made of any preferred dimensions, shape and number of core openings, Without liability of fract-uring the ar- Vticles or producing hair line cracks in same ein the operation of disengaging the articles from the co-operating parts of the apparatus.` Y 5 f Figure l of the dra-Wings is a perspective view, illustrating a molding apparatus constructed in accordance with my invention, used yfor producing a gypsum block of the general type now used extensively in the partitions andl Walls of buildings. Figure 2 is an enlarged vertical cross sectional vvieiv of said molding apparatus, showing one means `that can be used for in- -surino' the core shells retainine' substan-v tially their original shape and form; and y Figure 3 is a top plan view ofy a portion .of the article )roduced in the a3 aratus showing the internal supporting means for the core shell arrangedy in operativey position inside of same.

Referring to the drawings which illus-` trate thelpreferred form of my invention, A

designates a mold of any preferred shapeV and construction that is adapted to receive a plastic, self-hardening substance from which an article or structure is to be formed, such, for example, as a gypsum lstructures-C, each of which consists of a number ofv spaced shell engaging devices l carried by resilient members 2 which arelv connected at one end to a supporting member 3 and connected at theiropposite end to an actuating member a arranged inside of the supporting member 3 and adapted to be lsupporting member 3 is herein illustrated as consisting of a hollow' member rof .substantially the same cross-sectional shape as the /ingdevices l. As shown inFigure'2, the

ycore shell with which it is used, and the acslots 6 in the supporting supporting member 3 is provided With af plurality f sets of core engaging devices 1 ar 'anged in spaced relation, but, if desired,

vthe material supporting means for each core shell could be constructed'so as to support said shell throughout l Preferably, some suitable means,- such for example, as hooks 7 at the upper end of the supporting member-3. are provided fory ietaining the actuating memberv 4; after it has been moved longitudinally 'in a direct-ion to expand the shell vsupporting means C vor cause the shell engaging devices :l of said means to be forced outwardly intoj engagement with the shell inside yof `Which said means C is arranged. I Wish it to be under-1.

VVstood, however, that my invention is not ylimited to a molding apparatus provided with a collapsible means C of the kind herein illustrated for internally supporting the core shells, as the particular construction of said means is immaterial, so far as my broad idea is concerned, Furthermore, instead of using a collapsible structure to internally support the core shell, it Would be possible kto support said shell by a pneumatic medium i or by a member constructed of rubber.

The core shells B herein illustrated consist of corrugated cardboard tubes of substantially rectangular shape in cross section which are adapted to be arrangedvinside of the mold A preparatory to introducing the plastic substance into the mold and which are left inthe article or structure formed in the mold. Said shells can be of any preferred shape, and as previously stated, they can be constructed fromany material which is of sufliciently low cost to' justify itsuse and which is of such va nature that it will retain the plastic substance Wliile said substance is setting and will yield or give slightly in case the plastic substance expands and ygrips the core, as in the case of articles formed from gypsum. In producing an article with a molding apparatus embodying my invention the core shells B are first arranged inside of the mold A with the supporting means C for said shells positioned in same, and thereafter the substance from which the article is to be formed is introduced into the mold in a plastic condition. After said substance has set or partly hardened the shell supporting means C are collapsed and withdrawn from the shells B, and thereafter, the finished article is removed from the mold With the shells B left in place and constituting a part of the finished product. lVith such an apparatus there is little danger of the article being fractured during the operation of making the same, due, of course, to the fact that the shells B which form the hollow spaces or openings in the article are not removed from same, but, on the contrary, are left in the article. The apparatus is inexpensive to construct, it is easy to operate, and as it is only necessary1 to leave the supporting means C in the shells B for a` short period, namely, until the substance in the mold has solidified, the apparatus effects a considerable saving in the time required to produce cored articles from plastic substances. Such an apparatus can be used for producing pre-cast articles, or it can be used for molding a structure that is cast in place.

Having thus described my invention, what l claim as new and desire to secure by Letters Patent is:

l. A molding apparatus for plastic sub'- stances, comprising a mold, and a core shell formed of corrugated cardboard or inexpensive, non-rigid material arranged inside of said mold and adapted to be left in the article or structure formed in the mold.

2. A molding appara-tus for plastic substances, comprising a mold, a non-rigid core shell in said mold that is adapted to be left in the article or structure formed in the mold, a plurality of devices inside of said shell for maintaining the shell in substantially its original form, and means for disengaging the devices from the shell so as'to enable them to be withdrawn from the shell.

3. A molding apparatus, comprising a mold, a non-rigid core shell in said mold that is adapted to be left in the article or structure formed in the mold, and a col'- lapsible means for internally supporting said shell composed of a supporting member, resilient elements on the exterior of said supporting member connected at one end to said member, shell engaging devices carried by said resilient elements, and a longitudinally movable actuating member inside of said supporting member connected to the opposite end of said resilient elements and adapted to be lnoved longitudinally in opposite directions to move said shell engaging devices into and out of engagement with the shell.

FREDERICK A. K. MARX.v

other 

